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Question: How do We name alkanes, alkenes and alkynes\(?\)...

How do We name alkanes, alkenes and alkynes??

Explanation

Solution

Alkanes, alkenes and alkynes are hydrocarbons which are organic chemical compounds composed exclusively of hydrogen and carbon atoms, some substituents may be attached to them. They are generally named by following IUPAC Nomenclature, which has a set of rules for proper naming of compounds.

Complete step-by-step answer:
Alkanes, alkenes and alkynes are hydrocarbons and are exclusively composed of carbon and hydrogen atoms. Alkanes are the simplest hydrocarbon known to us, belonging to the family of saturated hydrocarbons i.e. they contain only sigma bond linkages between carbon and hydrogen atoms. On the other hand alkenes and alkynes are unsaturated hydrocarbons, while in alkenes, double bond linkages are seen, in alkynes, triple bond linkages can be found between carbon and hydrogen atoms.

For proper naming of these compounds we follow IUPAC Nomenclature which states:
(i)\left( i \right) First the longest hydrocarbon chain is selected and is termed as the parent chain in case of alkanes. While in the case of alkenes and alkynes, the hydrocarbon chain with the double and triple bond is chosen as the parent chain. The parent chain is named with the help of Greek alphabets such as prop, but, pent, hept, octprop,\,but,\,pent,\,hept,\,oct etc.

(ii)\left( {ii} \right)The parent chain is numbered such that we reach the double-bonded or triple bonded carbon atom earliest. Also if substituent is present the parent chain should be numbered such that we reach the substituent earliest. The position of the carbon atom with the double bond, triple bond or substituent is mentioned numerically.

(iii)\left( {iii} \right)For alkanes suffix ′−ane′' - ane' is used at the end, while for alkenes, the suffix ′−ene′' - ene' is used and for alkynes suffix ′−yne′' - yne' is used. In the case of multiple double bonds in the carbon chain, Greek numerical prefixes such as di, tri are used to denote their number.

Note: We should be careful while doing the IUPAC Nomenclature, priority must be given to the longest chain but if the shorter chain has double bond or triple bond present then it will become the parent chain. Also do not forget to add the suffixes at the end of the name of the given organic compound.